Cannot wipe with TWRP

I have G935F, installed TWRP 3.0.0.0 and rooted, WITHOUT wiping. System boots correctly, but I cannot do factory reset or wipe with TWRP, because I got some messages like "Cannot mount Data" and "Failed crypto loader". I understand that it has to do with encryption. Can someone please enlight me, and give me tips about the issue?

Thank you